1. Field of the Invention
This invention relates to light-transmitting fire resistant glazing panels of the type which comprises at least two vitreous sheets between which is sandwiched at least one intervening layer of intumescent material.
2. Description of the Related Art
There is a demand for such panels to afford a degree of personal protection in the event of a fire, and to delay the spread of the fire. On the exposure of the panel to the intense heat of a fire, the intumescent material, which is typically a hydrated alkali metal silicate, most often sodium silicate, foams and becomes opaque. It thus forms a barrier against the transmission of infra red radiation. Furthermore, in the event that one sheet, or even more, of the panel becomes broken due to thermal shock, such foamed intumescent material can be effective to maintain the fragments in position, so that the pan remains effective as a barrier against the passage of smoke and fumes.
Known panels of the type referred to are framed and may be secured in place by their frames in for example a window opening, or as transparent panels within a door.